Retrieve detailed statistics for a funnel, including a summary of key metrics
and optional per-step breakdowns of views, opt-ins, sales, and earnings.

Defaults to a 30-day timerange ending now. Override with timerange_start and
timerange_end. Timerange values are automatically clamped: future end dates
are clamped to now, windows exceeding 90 days are clamped to 90 days, and if
start is after end the window resets to 30 days ending at timerange_end.

By default the response includes a page_public_ids array. Use
expand[]=steps to receive a steps array with per-step metrics instead.

The metric names in the response are defined in Metric vocabulary in the Stats Skill, which also walks a recurring funnel auditor agent built on this endpoint.